(1) Field of the Invention
The present invention generally relates to real-time data capture and more particularly to real-time capture of vector CRT display data for use in a real-time hardcopy processing system.
(2) Description of the Prior Art
The Navy requires accurate duplication of visual sonar acoustic and symbolic data displayed on AN/UYQ-21(V) displays used in one of the AN/SQQ-28(V), AN/SQR-19(V), or AN/SQS-53X(V) sonar systems. The vector or sequential stroke displays such as that used by the AN/UYQ-21(V) display system utilize control circuitry to deflect the electron beam to draw symbols limited to a predefined set. The set of symbols may be a combination of alpha-numerics and custom symbols. To display a symbol, a control word is sent to the display which contains the X-Y coordinates indicating where the electron gun is to aim its electron beam. Another signal instructs the gun to increase or decrease the energy of the beam. The sequence of control words sent to the display will result in a picture on the CRT screen.
Previously, capture of data information used to create this type of display for use in a hardcopy processing system was achieved by post-processing of the data recorded on magnetic tape. This method requires capturing all of the data, storing it on magnetic tape for later retrieval, and post-processing to reproduce a hardcopy image. However, this method is impractical for real-time tactical use. An alternative to post-processing is to photographically reproduce the display; however, this results in poor image resolution.